BOSTON — For the second straight night, the third period was a charm for the defending national champion Boston University Terriers.

Zach Cohen’s power-play goal 5:33 into the final period snapped a 2-2 tie and Nick Bonino scored 2:15 later as the Terriers completed a weekend sweep of the Black Bears 5-2 at Agganis Arena Saturday night.

BU had scored three goals in a span of 3:34 on Friday night to extend a 4-3 lead en route to a 7-4 triumph.

BU improved to 13-12-3 overall, 10-9-2 in Hockey East with its fifth win in six games.

Maine fell to 14-11-3, 11-8-2, after being swept for the second time in eight series this season.

“They outworked us all weekend. I don’t know why. I don’t have an answer for it,” said Maine sophomore right wing and leading scorer Gustav Nyquist, who had two assists and a team-high five shots on goal after being held scoreless and without a shot on Friday.

“They played great,” said Bear sophomore defenseman Will O’Neill. “They came at us hard, gave us what they had and we couldn’t handle them.”

“We worked harder and played better than we did [Friday] but they still beat us to loose pucks, outchanced us in our own end and outworked us,” added Maine junior defenseman Josh Van Dyk.

BU outshot Maine 36-30 and attempted 70 shots to Maine’s 46. Kieran Millan made 28 saves while Maine’s Scott Darling finished with 31.

The Terriers used their superior speed, talent and tenacity to generate sustained forechecking pressure in the Maine zone while the Bears had limited pressure due to BU’s talented and mobile defense corps and effective backchecking by their forwards.

Junior defenseman Jeff Dimmen answered goals by Corey Trivino and Chris Connolly to erase a pair of one-goal deficits.

And Maine was on the power play early in the third period looking for its first lead of the series when David deKastrozza was assessed a tripping penalty in the offensive zone.

Maine had killed off BU’s first five power plays but Cohen made them pay this time when he came off the boards and parked himself at the top of the crease where he was able to lift the second rebound of a David Warsofsky point shot over Darling.

“The rebound came right out in between one of their defenseman’s skates. He couldn’t get it. I came right there and got the first rebound [shot] and it came right back to me and I put it under the crossbar,” explained Cohen.

An effective forecheck resulted in the Bonino goal as he darted to the net from the left side and had his pass intended for Ross Gaudet deflect in off Dimmen’s skate.

“Joe [Pereira] made a great pass to me and Ross went hard to the net. If it hadn’t hit [Dimmen’s] skates, Ross would have banged it in anyway,” said Bonino.

Any comeback aspirations were squashed by penalties as Maine gave the Terriers five straight power plays in the third period.

“We’ve got to be smarter than that,” said Van Dyk.

“We’ve played real well in the third period lately,” said Zach Cohen. “We’ve been making good plays and getting the puck deep. And with us moving our feet and not using our sticks as much, we’ve been able to draw penalties rather than take them.”

Eric Gryba added a power- play goal with 18 seconds left.

Trivino opened the scoring by pouncing on a loose puck between the faceoff dots and beating Darling to the far side.

Dimmen tied it with a screened power-play drive from the midpoint.

Connolly scored with a far corner backhander off a Pereira pass but Dimmen tied it by finishing off a perfectly executed give-and-go with Nyquist from the middle of the high slot.

“They just kept coming. Every time we thought we had a little momentum going, they’d come back down and make a push,” said Maine senior right wing Kevin Swallow.